I. Field of the Invention
This invention relates to whipstock assemblies used in a well and, in particular, to a hydraulically set anchor for use in a whipstock assembly to provide sufficient anchorage to facilitate kick-off from the primary well bore.
II. Description of the Prior Art
Packers and anchors are typically used in well bores to seal off sections of a well and/or to provide support structure for well tools in the production process. Deviating tools, whipstocks, perforating tools, etc. are examples of tools which employ an anchor or packer. In many instances, the anchor/packer is run into the well and set with one trip of the running string and the particular device engaged with the anchor/packer using a second trip of the running string. With the tool supported against the anchor/packer, the particular operation can be conducted.
More recently, in order to reduce production costs, the tool has been combined with the anchor/packer thereby eliminating one trip of the running string. Consequently, the anchor/packer is set in the well using mechanical or hydraulic means extending through the well tool after which the tool is engaged to carry out the operation. Once the operation is completed the anchor/packer is typically abandoned with the well.
In the prior known hydraulically set anchor/packer, the hydraulic pressure may have to be maintained in order to prevent release of the tool. As a result, mechanically set tools are typically used in one-trip combination assemblies since the mechanical set can be maintained following disconnection of the production tool. However, mechanically set anchor/packers are unreliable in high pressure wells because of the extreme setting forces required which cannot be achieved in such tools. Moreover, it has been found that in many applications, the well bore does not need to be sealed-off by packing elements.